The present invention relates to a card which incorporates a semiconductor integrated circuit (hereinafter referred to as xe2x80x9cICxe2x80x9d card) and more particularly to an IC card wherein an information processor mounted on an IC is used in common for both communication by a contact coupling with an external device through a connector and communication by a non-contact coupling through an antenna.
As known well, a contact type IC (Integrated Circuit) card is coupled through a connector to an external device, e.g., a data reader/writer (simply xe2x80x9creader/writerxe2x80x9d hereinafter) and performs transmission and reception of signals between it and the reader/writer while being supplied with electric power through the connector. On the other hand, a non-contact IC card couples to the reader/writer in a non-contact state through an antenna and performs transmission and reception of signals between it and the reader/writer while being supplied with electric power through the antenna.
Recently, a single card which permits either the above contact or non-contact type communications has been devised or being developed as a dual interface IC card (see, for example, Published Japanese Translations of PCT International Publication for Patent Applications No. Hei 10-505932). The dual interface IC card is convenient for users and therefore its application range is being widened.
FIG. 8 shows an internal circuit configuration of a conventional dual interface IC card. An internal circuit 2 is integrated into an IC chip. Electric power from a power supply and signals are supplied through a coiled antenna 1 in case of a non-contact type operation or through a connector 10 in case of a contact type operation. As bidirectional signals to and from an information processor 8, signals having gone through either the antenna 1 or the connector 10 are selected by a selector 22. For example, in the prior art being considered, the selection is made by a voltage detector 21 detecting that electric power has been fed to a terminal Vdd of the connector 10 and, as a result of the detection, the signals having gone through the connector 10 are selected.
In this way the information processor 8 is used in common by both contact and non-contact type communications. In the above conventional example, priority is given to the communication through the connector 10, namely, to a contact coupling to avoid simultaneous contact and non-contact operations.
Usually, the information processor 8 has a processing unit and a memory and reads the contents of the memory in accordance with directions given by a reader/writer and provides a transmission signal or rewrites the memory contents by use of a reception signal provided from the reader/writer.
As electric power in non-contact operation, a high frequency signal received by the antenna 1 is rectified and smoothed by a rectifier and smoothing circuit 3 and a DC output voltage is obtained as the electric power. On the other hand, electric power from the connector 10 is obtained through a terminal thereof directly from the reader/writer.
FIG. 9 shows a conventional example in which priority is given to a non-contact coupling side. In this example, a high frequency detector 23 for detecting a high frequency signal from the antenna 1 is used instead of the voltage detector 21 and the selecting operation of the selector 22 is controlled in accordance with whether a high frequency signal is present or not.
In the above-mentioned dual interface IC card, the IC can be caused to malfunction, for example, by intermitting the priority-side coupling while communication is made through a coupling on the non-priority side. It is possible that such a malfunction is caused to occur intentionally to conduct tampering (opening or altering the contents of IC without permission). It is the present situation that such an inconvenience cannot be avoided.
It is an object of the present invention to provide an IC card capable of preventing the occurrence of an abnormal state of coupling and thereby preventing an abnormal operation of IC.
For achieving the above-mentioned object, the IC card of the present invention is characterized by including a coupling detecting means for detecting a contact coupling and a non-contact coupling and a communication cut-off means which, when there are supplied electric power and a signal for inducing the other coupling during communication by one coupling, cuts off the communication so that the communication is performed by neither of the couplings. Thus, since all of communicating functions are cut off upon supply of electric power and a signal for inducing the other coupling, malfunction of IC is prevented.